The present invention relates to an execution time measurement device in a control unit and an execution time measurement method, and particularly to an execution time measurement device in a control unit and an execution time measurement method for measuring the execution time for multiple tasks that function as a priority-assigned application under the management of a real-time operating system mounted on a control unit.
The real-time property of control in an electronic control apparatus mounted on a mobile body such as a car presents a very important requirement. To be more specific, each task activated by the real-time operating system of the electronic control apparatus is required to complete running before the temporal deadline clearly defined for each task. This requires evaluation and management of worst-case execution time (the worse-case value for execution time) for each task.
An example of the art of measuring the task execution time of the electronic control apparatus is disclosed in the Japanese Laid-Open Patent Publication No. 2001-331343. This art allows the real-time operating system itself to send the time stamp at the time of activation and termination of tasks to an external tool in the form of log information. The external tool analyzes the information collectively, and measures the temporal behavior of each task in the off-board mode (outside the electronic control apparatus).
Examples of the art of measuring the task execution time in the on-board mode (inside the electronic control apparatus) is disclosed in the Japanese Laid-Open Patent Publication No. Hei 05-165655 and Japanese Laid-Open Patent Publication No. 2001-318807. According to this art, a special hardware counter is provided in an electronic control apparatus to measure the execution time of each task. The principle is that, upon the resumption of execution of the suspended task, the stored halfway value is re-loaded into the aforementioned hardware counter. This must be followed by the step of resuming the measurement. This requires an area where the aforementioned halfway value can be stored for each task.